Scanning systems for scanning multiple light beam systems, such as light curtains, have a plurality of light sources in an emitter column and a plurality of light receivers, each one associated with one light source, in a separate receiver column. Light curtains can be used for example in industrial safety applications to protect people working on dangerous machines in order to stop the machine if people enter a dangerous zone around the machine. The scanning system of such a light curtain is used to allow each individual light source to emit during a certain time window and the corresponding light receiver to receive accordingly. Beams are transmitted from respective individual light emitters to respective corresponding receivers in a sequential manner and the full light curtain is scanned every cycle.
In order to allow a full synchronization between the emitter column and the receiver column without a cable between the two units, an optical beam is often used as a synchronization beam. Light pulses emitted by the synchronization beam usually include coded information on the type of light curtain, the number of beams, the resolution of the light curtain and any other appropriate information. Using an optical synchronization beam between the emitter column and the receiver column ease the cabling of the light curtain as the emitter and receiver can be sometimes far away from one and other (up to 80 m in some applications) and often in a strong EMC environment.
It is believed that the scanning system and method, as indicated by the embodiments described herein, can be used to scan a safety light curtain in a more effective manner.